operations to assist aircraft in finding the best sampling areas. Prep- aration of the air radex area consisted of selecting an altitude at the bottom of the volume under consideration, considering this altitude as a surface plane, and constructing a hodograph using appropriate winds above the surface. Areas of possible contamination were then predicted by the use of diffusion factors applied to the resultant winds obtained, and modified to account for deviation from a point~source origin of fallout (Ref- erence 16, pp. 66 and 67). Offsite Monitoring Much of the CJTF 7 planning correspondence (Reference 16, Tab C) clearly shows concern for the safety of the native population on the var- ious atolls in the PPG. An 1l December 1953 communication to CINCPAC stated, "The decision to shoot should be reached with the understanding that no health hazard to. . . populated islands . .. will ensue." How- ever, CJTF 7 did not believe it necessary to monitor the islands for radioactivity, or to sample the drinking water of distant atolls -- a procedure followed during Operation IVY in 1952. CINCPAC did not completely concur. A 31 October 1953 letter directed CJTF 7 to sample drinking water in the event “that radiological conditions require." A later letter (11 February 1954) directed CJTF 7 to assist the AEC New York Operations Office, Health and Safety Laboratory (NYKOPO, HASL) in aerial monitoring of inhabited atolls in the Marshall, Mariana, and Western Caroline islands. The surveys were to be made only of those atolls where the possibility of contamination existed, rather than of all atolls as was done during Operation IVY. The aerial monitoring was conducted by aircraft operating from Kwajalein and Guam (VP-29) and from Oahu (VW-1). The radiation detection equip- ment was provided by the AEC, but AEC staff members did not participate in the monitoring flights. Table 9 lists the potential flights and the is-~ lands each flight was expected to monitor. Ground monitoring stations were established by HASL at Truk, Yap, Ponape, Kusaie, Majuro, Rongerik, Ujelang, Wake, and Midway. Automatic recorders continuously monitored gamma radiation; however, the upper limit 116